I was fortunate enough to have a second post published on the VMware SMB Blog site. This particular post is an issue that I faced quite a while back, but it still holds true if you are trying to relay vCenter alerts externally.
From the Bloggers Bench: Relay vCenter Alert Emails Externally
When configuring your vCenter environment, most if not all VMware Administrators will set up email alerting. I covered the configuration of this in Setting Up & configuring Alarms In vCenter Part 1.
Unfortunately, if you leave Exchange 2010 using its Default Receive Connector, you will only receive alerts internally e.g. to the domains which Exchange 2010 is authoritative. This causes a problem if you need to send alerts to a third party e.g. Managed Service Provider.
To demonstrate the issue, I have connected to a vCenter server and then I’m going to telnet to an Exchange 2010 CAS Server on port 25 by issuing the command:
telnet VMF-EX01 25
Once in enter the following:
MAIL FROM: email@example.com
RCPT TO: firstname.lastname@example.org
Read more over at the VMware SMB Blog